Over the years the demand for performance improvements in lubricating oils and functional fluids has persisted and, if anything, progressively increased. For example, lubricating oils for use in internal combustion engines, and in particular, in spark-ignition and diesel engines, are constantly being modified and improved to provide improved performance. Various organizations including the SAE (Society of Automotive Engineers), the ASTM (formerly the American Society for Testing Materials) and the API (American Petroleum Institute) as well as the automotive manufacturers continually seek to improve the performance of lubricating oils. Various standards have been established and modified over the years through the efforts of these organizations. As engines have increased in power output and complexity, and in many cases decreased in size, the performance requirements have been increased to provide lubricating oils that will exhibit a reduced tendency to deteriorate under conditions of use and thereby to reduce wear and the formation of such undesirable deposits as varnish, sludge, carbonaceous materials and resinous materials which tend to adhere to various engine parts and reduce the operational efficiency of the engine.
Current objectives include the development of additive formulations and lubricant compositions, especially crankcase lubricants and crankcase lubricant additive packages, capable of achieving these stringent performance requirements without requiring use of heavy metal-containing components, such as zinc dihydrocarbyl dithiophosphates. Because of environmental and conservational concerns, much emphasis of late has been devoted toward finding ways of eliminating heavy metal-containing components from lubricants and functional fluids. Not only do heavy metals pose environmental and toxicological problems (e.g., problems arising in the event of spillage, leaks, etc.), but their presence in used oils complicates used oil reclamation procedures.
Still another desirable objective is to provide additive formulations and lubricant compositions which exhibit good compatability with elastomeric substances utilized in the manufacture of seals, gaskets, clutch plate facings, diaphragms, and like parts. Unfortunately, commonly used additives containing basic nitrogen constituents tend to cause excessive degradation of such elastomers when oils containing such additives come in contact with such elastomers during actual service conditions.
A need thus exists for novel oleaginous compositions (i.e., lubricants and functional fluids) and additive formulations therefor which are capable of meeting stringent performance criteria including adequate compatibility with elastomeric substances, and which nonetheless are devoid of heavy metal-containing components.
There are literally hundreds, if not thousands, of patent disclosures describing attempts (some more successful than others) to improve the performance characteristics of oils of lubricating viscosity. The following is but a small selection from this vast body of literature.
U.S. Pat. Nos. 3,087,936 and 3,254,025 disclose forming oil-soluble nitrogen- and boron-containing compositions by treating an acylated nitrogen composition with a boron compound selected from boron oxide, boron halides, boron acids, and esters of boron acids.
U.S. Pat. No. 3,184,411 refers to producing lubricant additives by reacting a succinimide formed from an alkenyl succinic anhydride and a polyalkylene polyamine with phosphorus pentasulfide.
U.S. Pat. No. 3,185,645 teaches preparation of lubricant additives by reacting an alkenyl succinic anhydride, a dihydrocarbyl dithiophosphate and a polyalkylene polyamine.
U.S. Pat. No. 3,235,497 discloses formation of a lubricant additive by reacting a phosphorus sulfide such as phosphorus pentasulfide with a high boiling hydrocarbon, reacting the resulting phosphosulfurized hydrocarbon product with an alcohol to form an O-ester of a hydrocarbon thioacid of phosphorus, reacting this latter product with an olefinically unsaturated dicarboxylic acid or anhydride, and then reacting this resulting product with an amine containing one or more primary amino groups.
U.S. Pat. No. 3,265,618 describes formation of acid aryl phosphate salts of polybutenyl succinimides and their use with detergent polymers in lubricating oils.
U.S. Pat. Nos. 3,281,428 and 3,338,832 describe use as lubricating oil additives of products made by reacting a hydrocarbon-substituted succinic acid producing compound with an amido compound (RR'NH; R is H or a hydrocarbyl group and R' is amino, cyano, carbamyl or guanyl), and reacting this product with a boron compound (boron oxide, boron halide, boron acid, ammonium salt of boron acid or ester of boron acid).
U.S. Pat. No. 3,282,955 discloses preparation of lubricant additives by reacting a hydrocarbon-substituted succinic acid-producing compound with a hydroxyhydrocarbon amine and then reacting this product with a boron compound, namely a boron oxide, boron halide, boron acid, ammonium salt of boron acid or ester of boron acid.
U.S. Pat. No. 3,284,410 refers to forming a boron-containing product by reacting a hydrocarbon-substituted succinic acid compound with an alkylene amine, and a both a boron reactant and a cyanamido amido compound (RR'N--CN; R is hydrogen or alkyl, and R' is hydrogen, alkyl, or guanyl). The boron reactants are selected from boron acids, boron oxide, boron halides, ammonium salts of boron acids, and esters of boron acids with monohydric alcohols.
U.S. Pat. No. 3,324,032 teaches forming an additive for lubricating oil by forming a reaction product of dithiophosphoric acid and dibasic acid anhydride and then reacting this product with an amine or ammonia.
U.S. Pat. Nos. 3,325,567 and 3,403,102 disclose preparation of phosphorus-containing esters by reacting a polyhydric alcohol with (A) a hydrocarbon-substituted succinic acid or halide, ester or anhydride thereof, and (B) a phosphorus acid producing compound selected from phosphoric acids, phosphorus acids, and the halides, the esters, and the anhydrides thereof.
U.S. Pat. No. 3,344,069 refers to forming a boron-containing product by reacting a hydrocarbon-substituted succinic acid compound with an alkylene amine, and both a boron reactant and a polyhydric alcohol or a bisphenol or an aminoalkylphenol. The boron reactants are selected from boron acids, boron oxide, boron halides, ammonium salts of boron acids, and esters of boron acids with monohydric alcohols.
U.S. Pat. Nos. 3,502,677 and 3,513,093 describe preparation of substituted polyamines by the reaction of 1 mole of an alkylene amine with at least about 0.25 mole of a substantially hydrocarbon-substituted succinic acid-producing compound having at least about 50 aliphatic carbon atoms in the substantially hydrocarbon substituent and at least about 0.001 mole of a phosphorus acid-producing compound selected from the class consisting of phosphoric acids, phosphorous acids, phosphonyl acids, phosphinyl acids, and the esters, the halides, and the anhydrides thereof.
U.S. Pat. No. 3,511,780 refers to mineral oil-soluble detergent-dispersants prepared by reacting the condensation product of an alkenyl succinic anhydride and a polyamine (with or without a carboxylic acid) with an acidic reaction product of a phosphorus sulfide and a hydrocarbon and, in a modification, by treatment also with a dialkyldithiophosphorus acid. It is indicated that the additive can be used with conventional additives such as zinc dialkyldithiophosphate.
U.S. Pat. No. 3,533,945 describes use as a lubricating oil additive of a combined boron ester-alkenyl succinic acid ester of a polyhydric alcohol.
U.S. Pat. No. 3,623,985 teaches reacting an alkenyl succinimide with a compound such as cyanuric chloride, phosphoryl isocyanate, phosphorus oxytrichloride or phosphorothionic trichloride to form a product having three alkenyl succinimides bonded through an amine nitrogen to a central nucleus such as a triazine or phosphorus acid derivative. The products are indicated to find use as detergents and dispersants in lubricating oils.
U.S. Pat. No. 3,718,663 deals with preparation of oil-soluble boron derivatives of an alkylene polyamine-urea or thioureasuccinic anhydride addition product.
U.S. Pat. No. 3,865,740 is concerned with multifunctional lubricant additives which are N-substituted, S-aminomethyldithiophosphates, wherein the substituent is, among other things, a hydrocarbyl-substituted succinimide.
U.S. Pat. Nos. 3,950,341 and 3,991,056 refer to oil-soluble ashless detergent dispersants consisting of a reaction product obtained by reacting (a) an alkenyl dibasic acid or its anhydride with (b) an alcohol of the hindered type, and then reacting the so obtaining intermediate with (c) an amine or its derivative or analog, or with boric acid (or its anhydride) or phosphorus pentasulfide.
U.S. Pat. No. 4,097,389 discloses the formation of reaction products useful as detergents in lubricants, fuels or other industrial fluids. The products are made by reacting alkenyl succinic anhydride with an amino alcohol such as tris(hydroxymethyl)aminomethane, and then reacting this product with boric acid or an organoborate, organophosphonate or aldehyde.
U.S. Pat. No. 4,234,435 relates to carboxylic acid acylating agents derived from polyalkenes such as polybutenes, and a dibasic, carboxylic reactant such as maleic or fumaric acid or certain derivatives thereof. These acylating agents are characterized in that the polyalkenes from which they are derived have a Mn value of about 1300 to about 5000 and a Mw/Mn value of about 1.5 to about 4. The acylating agents are further characterized by the presence within their structure of at least 1.3 groups derived from the dibasic, carboxylic reactant for each equivalent weight of the groups derived from the polyalkene. The acylating agents can be reacted with a further reactant subject to being acylated such as polyethylene polyamines and polyols (e.g., pentaerythritol) to produce derivatives useful per se as lubricant additives or as intermediates to be subjected to post-treatment with various other chemical compounds and compositions to produce still other derivatives useful as lubricant additives. An extensive listing of post-treating reagents is set forth. Reference is made to addition to a lubricating oil containing a zinc dialkyldithiophosphate, a basic calcium sulfonate, a basic calcium sulfur-bridged alkylphenol and a sulfurized Diels-Alder adduct, in one case of a polybutenyl succinic ester-amide, and in another case of a polybutenyl succinimide of a polyamine.
U.S. Pat. Nos. 4,338,205 and 4,428,849 refer to treating alkenyl succinimides or borated alkenyl succinimides at elevated temperatures with an oil-soluble strong acid, such as an alkaryl sulfonic acid or a phosphoric acid, such as a dialkyl monoacid phosphate.
U.S. Pat. No. 4,554,086 describes as lubricant additives borate esters of hydrocarbyl-substituted mono- and bis-succinimides containing polyamine chain linked hydroxyacyl groups.
U.S. Pat. Nos. 4,615,826, 4,648,980 and 4,747,971 describe oil-soluble nitrogen-containing dispersant adducts with fluorophosphoric acid.
U.S. Pat. No. 4,634,543 pertains to shock absorber fluids which contain a boronated compound such as a boronated polyisobutenyl succinimide of an alkylene polyamine and also a phosphorous acid ester or a phosphoric acid ester or an amine salt of either such ester.
U.S. Pat. No. 4,857,214 describes oil-soluble reaction products of inorganic phosphorus containing acids or anhydrides with a boron compound and ashless dispersants such as alkenyl succinimides useful as antiwear/EP additives in lubricants.
U.S. Pat. No. 4,873,004 describes use in lubricants of alkyl or alkenyl-substituted succinimides in which the alkyl or alkenyl moiety has a number average molecular weight from 600 to 1300 and in which the average number of succinic groups per alkyl or alkenyl group is between 1.4 and 4.0. Use in a commercial package of a zinc dialkyldithiophosphate, an overbased calcium salicylate and a VI improver is disclosed. It is suggested that the succinimide may be post-treated with any of an array of post-treating agents.